Ever-increasing requirements for communications services strain spectrum resources on a global scale, and it is difficult for operators to obtain a new spectrum or available spectrums are extremely limited. In this case, multiplexing current 2G and 3G spectrums has become an important means of competition among the operators, and is referred to as spectrum refarming in the industry. The spectrum refarming performed on communications systems of two standards inevitably causes interference to each other.
In the prior art, interference is canceled in a filtering manner. Specifically, first, a preset filter coefficient table is queried according to whether there is narrowband interference in an input signal and according to a narrowband interference feature of the narrowband interference, so as to obtain a corresponding filter coefficient. Then, a time-domain digital notch filter is configured according to the obtained filter coefficient. Finally, the narrowband interference is filtered out by using the configured time-domain digital notch filter.
However, because a passband and a stopband of a filter need to be correspondingly adjusted as system bandwidth and interference distribution change, a large quantity of preset filter coefficients need to be stored for various system bandwidth and interference distributions. The method is relatively complex, less flexible, and difficult to implement.